This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides a window mill with retractable blades, and a window milling and wellbore drilling system.
Window mills (e.g., lead mills, “watermelon” or barrel mills, etc.) are used to cut windows through wellbore linings (such as casing or liner). Whipstock assemblies include deflectors which deflect window mills laterally, in order to cut the windows. It will be appreciated that improvements are continually needed in the arts of constructing and operating window mills and whipstock assemblies.